The broad objective of this proposal is to promote significant research on an animal model, the small nematode Caenorhabditis elegans. This is to be achieved by continuing the activities of the Caenorhabditis Genetics Center (CGC) as the center for the acquisition, maintenance, and distribution of genetically and phenotypically characterized nematode stocks, with emphasis on the species Caenorhabditis elegans. Most of what is proposed in this application is an extension of the ongoing work of the CGC. The CGC plans to continue its acquisition of strains carrying reference alleles of all mapped genes and all available chromosome rearrangements. The core strain collection is maintained in liquid nitrogen. Strains will continue to be distributed upon request to laboratories conducting C. elegans research. A system of user fees will be instituted. The services of the CGC will continue to be publicized. Information about strains that are added to the CGC collection will be acquired and made available on the World Wide Web.